Surge suppression circuit and surge suppression method for single-phase alternating current power supply

Abstract

A single-phase alternating current power supply surge suppression circuit comprises a differential mode surge suppression circuit and a common mode surge suppression circuit, the differential mode surge suppression circuit comprises a second surge suppression branch, a third surge suppression branch, a fourth surge suppression branch and a seventh surge suppression branch, and the common mode surge suppression circuit comprises a first surge suppression branch. And a fifth surge suppression branch and a sixth surge suppression branch, wherein the seven surge suppression branches are sequentially connected in parallel between the input end and the output end. The invention further comprises a surge suppression method, surge energy is discharged in sequence in a step-by-step discharging mode, and then the protected circuit works normally.

Description

Technical field:

[0001] The present invention relates to the field of electronic technology, and in particular to a single-phase AC power supply surge suppression circuit and a surge suppression method. Background technology:

[0002] Surge is a sudden transient voltage or current pulse, which is essentially a violent pulse at the microsecond level. In industries such as aerospace and communications, when a surge occurs, the single-phase AC power supply is not only required to withstand the impact of the transient current spike, but also to operate normally and reliably.

[0003] For most circuits, if there is no reliable surge suppression circuit, when a surge occurs, a momentary large current pulse may appear inside the circuit or even at the DC output end. Large current pulses may reduce the reliability of semiconductor components, damage them, or even cause power failures; they may also cause abnormal output voltage or current and electromagnetic interference, affecting the operation of the next-level equipment. Therefore, it is of great significance to study surge suppression circuits and surge protection methods. Summary of the invention:

[0004] The present invention proposes a single-phase AC power surge suppression circuit and a surge suppression method. The proposed surge suppression circuit consists of seven surge suppression branches, wherein the first surge suppression branch consists of two Y capacitors connected in series, one end of the first Y capacitor is connected to the input end L line, and the other end is connected to the PE line, one end of the second Y capacitor is connected to the PE line, and the other end is connected to the N line; when a surge current with a higher frequency and a higher amplitude invades the circuit from the L line and the N line, the Y capacitor discharges the surge current to the PE line.

[0005] The second surge suppression branch is composed of a varistor, and the third surge suppression branch is composed of a transient suppression diode. Since the varistor has a higher clamping voltage and a stronger peak current bearing capacity, the varistor is arranged in front of the transient suppression diode. A fuse is connected in series between the second surge suppression branch and the first surge suppression branch. The function of the fuse is that when the overvoltage value exceeds the transient suppression diode varistor threshold, the fuse can be reliably melted.

[0006] The fourth surge suppression branch is composed of an X capacitor to discharge the surge current that is not effectively suppressed by the first three branches. The fifth surge suppression branch is composed of a common mode inductor and a gas discharge tube. Under energy impact, the gas discharge tube is connected in parallel at both ends of the common mode inductor to maximize the effect. When a surge occurs, a surge current with a higher amplitude will induce an induced voltage with a higher amplitude at both ends of the common mode inductor. When the induced voltage exceeds the nominal voltage of the gas discharge tube, the gas discharge tube generates an arc discharge to discharge the surge energy.

[0007] The sixth surge suppression branch is composed of two Y capacitors connected in series, and the structure of the sixth surge suppression branch is consistent with the structure of the first surge suppression branch. The seventh surge suppression branch is composed of an X capacitor, and the structure of the seventh surge suppression branch is consistent with the structure of the fourth surge suppression branch. The sixth surge suppression branch and the seventh surge suppression branch jointly discharge the surge current that is not suppressed by the previous stage.

[0008] When a surge occurs, the differential mode surge is discharged from the L line to the N line or from the N line to the L line through the parallel surge suppression branch, and the common mode surge is discharged to the PE line. The differential mode surge suppression circuit and the common mode surge suppression circuit suppress surge energies of different natures respectively. The common mode surge current is discharged through the first surge suppression branch, and the differential mode surge current is discharged through the transient suppression diode of the second surge suppression branch. When part of the differential mode surge current is discharged through the second surge suppression branch, it is discharged again by the varistor in the third surge suppression branch and the X capacitor of the fourth surge suppression branch. The common mode surge current not discharged by the first surge suppression branch is discharged through the gas discharge tube of the fifth surge suppression branch. The surge energy not discharged by the previous surge suppression branch is discharged again through the sixth and seventh surge suppression branches. In this way, the surge current is eliminated one by one, so as to discharge the energy more effectively and protect the subsequent circuit.

[0009] In addition, energy is discharged at both ends of the common-mode inductor in the form of tip discharge, and windows are opened on the surface of the discharge teeth without paint, so that the transient high voltage generated at both ends of the common-mode inductor can be discharged through the tip of the discharge teeth.

[0010] The single-phase AC power surge suppression circuit and surge suppression method provided by the present invention usually protect the protected circuit in the form of a printed circuit board, carry out normal operation of the components of the protected circuit and the printed circuit board of the protected circuit, and at the same time carry out the protection work of its own components and its own printed circuit board. Description of the drawings:

[0011] Figure 1 It is based on the open circuit voltage and short circuit current waveform of the surge standard IEC61000-4-5;

[0012] Figure 2 The invention provides a single-phase AC power surge suppression circuit;

[0013] Figure 3 It is the PCB discharge tip design proposed by the present invention;

[0014] Figure 4 This is the experimental waveform of the single-phase AC power supply differential mode surge test voltage of the embodiment of the present invention when the L and N phase difference is 90°;

[0015] Figure 5This is the experimental waveform when the differential mode surge test voltage is 2kV and the phase difference between L and N is 90° after the single-phase AC power supply of the embodiment of the present invention is equipped with a surge suppression circuit;

[0016] Figure 6 This is the experimental waveform of the single-phase AC power supply common mode surge test voltage of 250V and the phase difference between L and N is 90° in the embodiment of the present invention;

[0017] Figure 7 This is the experimental waveform when the common mode surge test voltage is 4kV and the phase difference between L and N is 90° after the single-phase AC power supply of the embodiment of the present invention is equipped with a surge suppression circuit; Specific implementation method:

[0018] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Surge is a sudden transient voltage or current pulse, which is essentially a violent pulse at the microsecond level. In industries such as aerospace and communications, when a surge occurs, the single-phase AC power supply is not only required to withstand the impact of the transient current spike, but also to operate normally and reliably.

[0020] For most single-phase AC power supplies, if there is no reliable surge suppression circuit, when a surge occurs, a momentary large current pulse may appear inside the circuit or even at the DC output end. Large current pulses may reduce the reliability of semiconductor components, damage them, or even cause power failures; they may also cause abnormal output voltage and current and electromagnetic interference, affecting the operation of the next-level equipment. Therefore, it is of great significance to study the surge suppression method of single-phase AC power supplies.

[0021] For single-phase AC power supply, there are two main sources of surge. When the power is powered on, a huge current will be generated to charge the internal energy storage capacitor. This current is the surge current. At the same time, when lightning strikes, a huge surge current will also be generated.

[0022] Due to differences in single-phase AC power supply structure, device parameters or lightning strike environment, there are differences in surge voltage or current. There are a series of standards for surge test methods, but most of the standards directly or indirectly refer to IEC61000-4-5 or the national standard GB / T17626.5. The two standards are basically the same, and both stipulate the equipment's immunity requirements for unipolar surges caused by switching and lightning transient overvoltages. According to standard IEC61000-4-5, there are five main parameters that characterize the surge waveform characteristics, as shown in Table 1. The open-circuit voltage and short-circuit current waveforms of the surge generator are as follows: Figure 1 shown.

[0023] Table 1 Surge characteristic parameters

[0024]

[0025] Surge is a transient energy, which is easily transmitted to the next stage through the parasitic capacitance of the components in the circuit. The surge suppression circuit should not only suppress surges, but also take into account electromagnetic compatibility. The surge suppression circuit proposed in the present invention is mainly composed of components such as varistor, transient suppression diode, gas discharge tube, X capacitor, Y capacitor and common mode inductor. Figure 2 shown.

[0026] Overvoltage protection components such as varistors, transient suppression diodes, and gas discharge tubes have the same volt-ampere characteristics. When the voltage across the component is higher than the nominal voltage, the component is in a low-resistance state, and the surge current can be discharged through the component. When the voltage across the component is lower than the nominal voltage, the component is in a high-resistance state. When the voltage across the component exceeds the maximum limit voltage, the component will break down and be damaged and cannot recover on its own. Therefore, when the overvoltage value is too high, the fuse should be reliably blown to ensure that components such as the varistor or transient suppression diode are not damaged.

[0027] Under energy impact, the gas discharge tube can play the maximum effect when connected in parallel at both ends of the common mode inductor. When a surge occurs, the high-amplitude surge current will induce a high-amplitude induced voltage at both ends of the common mode inductor. When the induced voltage exceeds the nominal voltage of the gas discharge tube, the gas discharge tube generates arc discharge to discharge the surge energy. In addition, the energy can be discharged by the tip discharge of the PCB board, and the surface of the discharge tooth is opened without painting, such as Figure 3 shown.

[0028] Discharge teeth are placed at both ends of the common-mode inductor, and windows are opened on the surface of the discharge teeth without applying paint, so that the transient high voltage generated at both ends of the common-mode inductor can be discharged through the tips of the discharge teeth, thereby reducing or even avoiding discharge through other paths. This method can effectively protect surrounding and subsequent devices.

[0029] When a surge occurs, the common-mode surge current is discharged through the first surge suppression branch, and the differential-mode surge current is discharged through the varistor of the second surge suppression branch. When part of the differential-mode surge current is discharged through the second surge suppression branch, it is discharged again by the transient suppression diode in the third surge suppression branch and the X capacitor of the fourth surge suppression branch. The common-mode surge current not discharged by the first surge suppression branch is discharged through the gas discharge tube of the fifth surge suppression branch. The surge energy not discharged by the previous surge suppression branch is discharged again through the sixth and seventh surge suppression branches. In this way, the surge currents are eliminated one by one, thereby discharging energy more effectively and protecting the subsequent circuits.

[0030] An embodiment of the present invention is as follows: In order to verify the surge suppression method proposed in the present invention, a 1.2kW principle prototype is developed. The prototype has two outputs, one outputs a DC voltage of 54V as the main voltage output, and the other outputs a DC voltage of 12V as the auxiliary voltage output.

[0031] According to the IEC61000-4-5 standard, a 250V differential mode surge test experiment was conducted on the prototype without surge suppression circuit using a surge generator when the phase difference between the L phase and the N phase was 0°, 90°, 180° and 270°, respectively. The main output voltage restarted, and the experimental waveform was as follows: Figure 4 The prototype is equipped with the surge suppression circuit designed by the present invention. According to the IEC61000-4-5 standard, a surge generator is used to perform 1kV, 1.5kV, and 2kV differential mode surge tests on the prototype equipped with the surge suppression circuit when the phase difference between the L phase and the N phase is 0°, 90°, 180°, and 270°, respectively. The prototype works normally and successfully passes the IEC61000-4-5 test level 4 test. The experimental waveform is shown in FIG. Figure 5 The differential mode surge test process is shown in Table 2.

[0032] Table 2 Differential mode surge test results

[0033]

[0034] According to the IEC61000-4-5 standard, a 250V common mode surge test experiment was conducted on the prototype without surge suppression circuit using a surge generator when the phase difference between L phase and N phase was 0°, 90°, 180° and 270°, respectively. The main circuit had no output voltage phenomenon, and the experimental waveform was as follows: Figure 6The prototype is equipped with the surge suppression circuit designed by the present invention. According to the IEC61000-4-5 standard, a surge generating device is used to perform 1kV, 2kV, 3kV, 3.5kV, and 4kV common mode surge tests on the prototype equipped with the surge suppression circuit when the phase difference between the L phase and the N phase is 0°, 90°, 180°, and 270°, respectively. The prototype works normally and successfully passes the IEC61000-4-5 test level 4 test. The experimental waveform is shown in Figure 7 The common mode surge test experimental process is shown in Table 3.

[0035] Table 3 Common mode surge test results

[0036]

[0037] It should be noted that, in this document, relational terms such as first and second are merely used to distinguish one physical structure from another physical structure, but do not necessarily require or imply any actual relationship or order between these structures.

[0038] Finally, it should be noted that the above is only a preferred embodiment of the present invention, which is only used to illustrate the technical solution of the present invention, and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A single-phase AC power surge suppression circuit, comprising a differential mode surge suppression circuit and a common mode surge suppression circuit, wherein: The differential mode surge suppression circuit includes a second surge suppression branch, a third surge suppression branch, a fourth surge suppression branch and a seventh surge suppression branch, and the common mode surge suppression circuit includes a first surge suppression branch, a fifth surge suppression branch and a sixth surge suppression branch. The seven surge suppression branches are connected in parallel between the input end and the output end in sequence.

2. According to the single-phase AC power surge suppression circuit of claim 1, the first surge suppression branch is composed of two Y capacitors connected in series, one end of the first Y capacitor is connected to the input end L line, and the other end is connected to the PE line, one end of the second Y capacitor is connected to the PE line, and the other end is connected to the N line, the second surge suppression branch is composed of a varistor, and a fuse is connected in series between the second surge suppression branch and the first surge suppression branch, the third surge suppression branch is composed of a transient suppression diode, the fourth surge suppression branch is composed of an X capacitor, the fifth surge suppression branch is composed of a common mode inductor and a gas discharge tube, and the gas discharge tube is connected in parallel at both ends of the common mode inductor, the sixth surge suppression branch is composed of two Y capacitors connected in series, and the structure of the sixth surge suppression branch is consistent with that of the first surge suppression branch, and the seventh surge suppression branch is composed of an X capacitor, and the structure of the seventh surge suppression branch is consistent with that of the fourth surge suppression branch.

3. A surge suppression method, applied to the single-phase AC power supply surge suppression circuit described in claim 1, specifically, discharging the differential mode surge from the L line to the N line or from the N line to the L line through parallel surge suppression branches, discharging the common mode surge to the PE line, suppressing surge energies of different properties respectively through the differential mode surge suppression circuit and the common mode surge suppression circuit, absorbing the differential mode surge and clamping the surge voltage through the surge suppression second branch, the surge suppression third branch, the surge suppression fourth branch and the surge suppression seventh branch, absorbing the common mode surge through the surge suppression first branch, the surge suppression fifth branch and the surge suppression sixth branch, and connecting the gas discharge tube in parallel at both ends of the common mode inductor to discharge energy.

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